Earlier quoted context omitted.
I think that one problem that eventually happens with this approach, which is a problem I had with Duolingo as well, is that very soon after learning a few words you need to start learning basic grammar. In these approaches that don't explain the grammar at all, you need to spend effort pattern matching to pick up the right grammatical rules to construct your own sentences, and you are never sure that you're doing th…
Just one more anecdote, but this is what turned me off from duolingo completely. You can't just learn words or sentences alone, you have to have at least some grammar in there. You need lists of prepositions and pronouns, and you need a little bit of at least simple rules for verbs and nouns. Yes, it's boring but otherwise you'll really struggle.
But I've found ~15 minutes per day to be fairly helpful in conjunction with other activities.